FSCN (File Format)

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The FSCN (caFe SCeNe animation) subfile stores scene animations controlling fog, light and camera settings. It appears as a subfile of a BFRES file in the 10th index group. Unless otherwise noted, all offsets in the file are relative to themselves.

Format

An FSCN file begins with an FSCN header. This is then followed by a number of sections pointed to by the header, many of which can occur multiple times. The purpose of these sections is described in the table below.

FSCN shares many similarities with the FSKA, FSHU, FTXP, FVIS and FSHA subfiles, which mostly only differ in the structure describing what is changed by animations over time, but reusing the same animation curve and key structures, and even headers being very similar to one another.

Header (FSCN)

Every FSCN begins with an 0x24 byte FSCN header. Beyond the general subfile fields it stores the entry number and location of Camera, Fog and Light Animation index groups.

Offset Size Type Description
0x00 4 Char[4] "FSCN" file identifier, ASCII string.
0x04 4 Int32 File name offset (without file extension).
0x08 4 Int32 File path offset, the path of the file this data was originally created from. Stripped in Mario Kart 8 files, always pointing to an empty string at the end of the BFRES string table.
0x0C 2 UInt16 User Data entry count.
0x0E 2 UInt16 Camera Animation count, the number of elements in the Camera Animation index group.
0x10 2 UInt16 Light Animation count, the number of elements in the Light Animation index group.
0x12 2 UInt16 Fog Animation count, the number of elements in the Fog Animation index group
0x14 4 Int32 Camera Animation index group offset.
0x18 4 Int32 Light Animation index group offset.
0x1C 4 Int32 Fog Animation index group offset.
0x20 4 Int32 User Data index group offset.
0x24 End of FSCN header

Camera Animation (FCAM)

A Camera Animation can modify visual parameters which control the cameera parameters like the field of view, aspect ratio, position, rotation or clipping planes. The header is of 0x24 bytes size.

Offset Size Type Description
0x00 4 Char[4] "FCAM" section identifier, ASCII string.
0x04 2 UInt16 Flags. Set of bits packed as xxxxxPxR xxxxxLxB, controlling how to play the animation and what data is stored. The following flags are possible:
  • B determines whether curve data is baked; baked if set.
  • L determines whether the animation is looping; looping if set.
  • R determines whether an Euler ZXY rotation (bit set) is stored or an aim direction (bit unset).
  • P determines whether a perspective projection (bit set) or orthographic projection is used (bit unset).
0x06 2 Padding.
0x08 4 Int32 Frame count.
0x0C 1 Byte Curve count, the number of elements in the Curve array.
0x0D 1 Padding.
0x0E 2 UInt16 User Data entry count (for this section).
0x10 4 UInt32 Baked length.
0x14 4 Int32 Name offset of this animation.
0x18 4 Int32 Curve array offset.
0x1C 4 Int32 Base Camera Animation Data offset, storing the initial state of the camera.
0x20 4 Int32 User Data index group offset (for this section).
0x24 End of Camera Animation (FCAM)

Camera Animation Data

The Camera Animation header points to a Camera Animation Result structure of 0x2C bytes size. The Curve target type is an offset into this structure to animate the corresponding field.

Offset Size Type Description
0x00 4 Single Near clipping plane distance. Polygons closer to the camera than this distance are not drawn.
0x04 4 Single Far clipping plane distance. Polygons further away to the camera than this distance are not drawn.
0x08 4 Single Aspect ratio of the projected world.
0x0C 4 Single Height offset of the camera or Field of View angle.
0x10 12 Single[3] Position of the camera.
0x1C 12 Single[3] Rotation (aim direction) of the camera.
0x28 4 Single Twist of the camera.
0x2C End of Camera Animation Data

Light Animation (FLIT)

A Light Animation can modify light parameters like light type, intensity or attenuation. The header is of 0x30 bytes size.

Offset Size Type Description
0x00 4 Char[4] "FLIT" section identifier, ASCII string.
0x04 2 UInt16 Flags. Set of bits packed as PPPPPPPC xxxxxLxB, controlling how to play the animation and what data is stored. The following flags are possible:
  • B determines whether curve data is baked; baked if set.
  • L determines whether the animation is looping; looping if set.
  • C determines whether the curve is enabled.
  • PPPPPPP are combinable flags with following meaning, controlling which base values are stored:
Value Description
1 Enable Light
2 Position
4 Rotation / Direction
8 Distance Attenuation
16 Angle Attenuation
32 First Color
64 Second Color
0x06 2 UInt16 User Data entry count (for this section).
0x08 4 Int32 Frame count.
0x0C 1 Byte Curve count, the number of elements in the Curve array.
0x0D 1 SByte Light type, determining what kind of light source is simulated.
0x0E 1 SByte Distance Attenuation function index.
0x0F 1 SByte Angle Attenuation function index.
0x10 4 UInt32 Baked length.
0x14 4 Int32 Name offset of this animation.
0x18 4 Int32 Light type name offset. Points to a string being either "ambient", "directional", "point" or "spot".
0x1C 4 Int32 Distance Attenuation function name offset.
0x20 4 Int32 Angle Attenuation function name offset.
0x24 4 Int32 Curve array offset.
0x28 4 Int32 Base Light Animation Data offset, storing the initial state of the light.
0x2C 4 Int32 User Data index group offset (for this section).
0x30 End of Light Animation (FLIT)

Light Animation Data

The Light Animation header points to a Light Animation Result structure of max. 0x44 bytes size. Only the elements appearing in the Flags are stored, in the order as follows. The Curve target type is an offset into this structure to animate the corresponding field.

Size Type Description
4 Int32 Enable the light or disable it.
12 Single[3] Position of the light.
12 Single[3] Rotation (aim direction) of the light.
8 Single[2] Distance Attenuation.
8 Single[2] Angle Attenuation.
12 Single[3] First color, stored as an RGB floating point vector.
12 Single[3] Second color, stored as an RGB floating point vector.
End of Light Animation Data

Fog Animation (FFOG)

A Fog Animation can modify fog parameters like distance or color. The header is of 0x30 bytes size.

Offset Size Type Description
0x00 4 Char[4] "FFOG" section identifier, ASCII string.
0x04 2 UInt16 Flags. Set of bits packed as xxxxxxxx xxxxxLxB, controlling how to play the animation and what data is stored. The following flags are possible:
  • B determines whether curve data is baked; baked if set.
  • L determines whether the animation is looping; looping if set.
0x06 2 Padding.
0x08 4 Int32 Frame count.
0x0C 1 Byte Curve count, the number of elements in the Curve array.
0x0D 1 Byte Distance Attenuation function index.
0x0E 2 UInt16 User Data entry count (for this section).
0x10 4 UInt32 Baked length.
0x14 4 Int32 Name offset of this animation.
0x18 4 Int32 Distance Attenuation function name offset.
0x24 4 Int32 Curve array offset.
0x28 4 Int32 Base Fog Animation Data offset, storing the initial state of the fog.
0x2C 4 Int32 User Data index group offset (for this section).
0x30 End of Fog Animation (FFOG)

Fog Animation Data

The Fog Animation header points to a Fog Animation Result structure of 0x14 bytes size. It apparently stores the initial state of the fog. The Curve target type is an offset into this structure to animate the corresponding field.

Offset Size Type Description
0x00 8 Single[2] Distance Attenuation.
0x08 12 Single[3] Color of the fog.
0x14 End of Fog Animation Data


Curve

Curves store how animations are performed over time and store the required keys and values for this. They appear in multiple animation subfiles, and their header is of 0x24 bytes size (for BFRES versions earlier than 3.4.0.0, they are of 0x20 bytes size).

Offset Size Type Description
0x00 2 UInt16 Flags. Sets of bits packed as xxxxxxxx xCCCKKFF.
  • FF determines the data type of frames in the Frame array.
Value Size Type
0 4 Single
1 2 16-bit fixed point value (1 bit sign, 10 bits integral and 5 bits fractional).
  • To convert to Single, use Float(x) / (1 << 5).
  • To retrieve from Single, use Round(x * (1 << 5))
2 1 Byte
  • KK determines the data type of keys in the Key array.
Value Size Type
0 4 Single
1 2 Int16
2 1 SByte
  • CCC determines what kind of curve data is stored, resulting in a different number of elements stored per Key. They are used to set the key values and control the interpolation from one key to the next.
Value Description Elements per Key
0 Cubic Single 4 (hermite interpolation)
1 Linear Single 2 (linear interpolation)
2 Baked Single 1 (no interpolation)
4 Step Integer 1 (no interpolation)
5 Baked Integer 1 (no interpolation)
6 Step Boolean 1 (no interpolation)
7 Baked Boolean 1 (no interpolation)
0x02 2 UInt16 Key count.
0x04 4 UInt32 Target Offset, an offset in bytes into the corresponding Animation Data structure to animate the field at that relative address.
0x08 4 Single Start frame, the first frame at which a key is placed.
0x0C 4 Single End frame, the last frame at which a key is placed.
0x10 4 Int32 / Single Data scale, multiplier to the raw key values to get the final result. Together with Data offset, it is chosen carefully to consider an optimal granularity between the stored values.
0x14 4 Single Data offset, added to the raw values (after multiplying them with Data scale) to get the final key value.
if BFRES version >= 3.4.0.0
0x18 4 Single Data delta, stores the difference between the first and last key value.
0x1C 4 Int32 Frame array offset.
0x20 4 Int32 Key array offset.
0x24 End of Curve
else
0x18 4 Int32 Frame array offset.
0x1C 4 Int32 Key array offset.
0x20 End of Curve

Frames

The Curve header points to a Frame array which stores values controlling at which frame a Key from the Key array is placed. Thus, the array has as many elements as specified in Key count. The data type of the frames is given in the Curve's Flags.

The end of the array is aligned to 4 bytes.

Keys

The Curve header points to a Key array which stores the key values and additional values to interpolate the curve from one point to the next. Thus, the array has as many elements as specified in Key count, multiplied by the number of elements stored per key (depending upon the CCC Curve Type bits in the Curve Flags as described above). The data type of each element is given by the KK Key Type bits in the Curve Flags.

The end of the array is aligned to 4 bytes.

Step Curves

The elements apparently represent the key values directly.

Linear Curves

For linearly interpolated curves, 2 elements are stored per key:

  1. Value at which the key is set. To get the final value, scale and then offset it.
  2. Delta to value at next frame to which the curve linearly runs. To get the final value, scale it. If there is no next frame, this is always 0.

A key can be discarded by the next key if that one is stored at the same frame. In that case, only the value of the next key is stored, and the delta of the previous key is adjusted to run to the value of the now discarded key.

This example curve's keys are stored as SByte elements. The curve scale was computed as 2, the offset as 200 and the curve delta (if available in the BFRES version) as 300. Due to the lower key in frame 20 being discarded in favor of the higher key, only 3 keys are stored in 6 elements as follows.

NW4FCurveExampleLinear.png
Point Array Index Raw Value *2 (Scale) +200 (Offset) Notes
0,0 0 -100 -200 0 Initial key with value 0.
(20,254) 1 127 254 - Delta to end value of initial key at next frame.
20,254 - - - - This key is discarded in favor of the next.
20,400 2 100 200 400 Overrides previous key.
(30,300) 3 -50 -100 - End value of overriding key at next frame.
30,300 4 50 100 300 Value of fourth (but third stored) key.
(end) 5 0 0 - Since no frame follows, always 0.


Hermite Curves

For hermite curves, 4 elements are stored for each key. It is unclear how to exactly interprete them to form the curve out of it.